Lost was not a cheap show to make. That feature length pilot episode cost somewhere in the region of $10 million, which puts it up there with your smaller-scale Hollywood productions; at the time, the average budget for a TV pilot episode was more like $4 million. It was such a risky and costly move that Disney, ABC's parent company, actually fired network head Lloyd Braun for the decision. Then Lost debuted, was a huge hit, and they were kind of committed to carrying it on. After all, it was ratings gold. Ratings gold that by virtue of being set on a desert island was mostly shot on location, in Hawaii, which cost a heck of a lot more than if they'd just build a few sets they could re-use all the time like most weekly dramas. Between the large cast and location shooting Lost cost $4 million per episode to make. That wasn't in the original plan, however; the initial pitch for the show suggested that the characters would live in a primitive Melrose Place (referencing the soap opera set in an apartment complex) that could be built on a soundstage.
Tom Baker is the Comics Editor at WhatCulture! He's heard all the Doctor Who jokes, but not many about Randall and Hopkirk. He also blogs at http://communibearsilostate.wordpress.com/